A camera is a device that is often employed to capture images or video. The data captured by the camera is used in a variety of different purposes and contexts. For example, a wearable device may include one or more onboard cameras to provide image data for the surrounding environment around the user of that wearable device. One example is the stereoscopic wearable glasses that features two forward-oriented cameras configured to capture images for an augmented reality presentation to the user through stereoscopic displays. The wearable glasses may also include backwards-oriented cameras to capture images of the user's eyes.
Camera calibration is often performed to ensure the precision and accuracy of camera, as well as the information extracted from the image data captured by the camera. The camera calibration process determines the true parameters of a camera device that produces an image, which allows for determination of calibration data of the camera such as intrinsic parameters and extrinsic parameters. The intrinsic parameters include, but are not limited to, focal point, focal length, principal point, and distortion coefficients. The extrinsic parameters include, but are not limited to, positional relationships between multiple cameras, and translational and rotational offsets between sensors.
Conventionally, the camera calibration process is performed by manually moving a single checkerboard target through a large set of different poses. At each pose, the checkerboard target is held completely still while the camera captures an image of the target, while ensuring that the entirety of the checkerboard is maintained within the camera's field of view. The cycle continues until all of the poses have been processed.
There are numerous disadvantages with this type of calibration process, since this approach is extremely laborious and time consuming. Moreover, the requirement to move the target through the numerous poses introduces significant possibility of variability into the calibration process and increased inability to obtain repeatable results unless costly and complicated target movement devices are introduced, which creates yet more expense and complications for the calibration process. These problems mean that the conventional camera calibration process is unusable in a high-volume manufacturing where large numbers of cameras need to be calibrated in a time-efficient and repeatable manner.
Therefore, there is a need for an improved approach to implement camera calibration.